FIELD OF THE INVENTION
The invention relates to a device for automatically adjusting a fold in a folding apparatus of a rotary printing machine.
A variable folding unit for web-fed rotary printing machines has become known in the prior art from German Patent 12 79 033, wherein a folding cylinder formed of a gripper part and a folding-blade part has two planetary-gear drives as well as two clutches. The folding-blade part is adjustable in circumferential direction by one of the planetary-gear drives, while a control cam for the gripper part is adjustable by the other planetary-gear drive. The adjustment of the folding-blade part and of the gripper-control cam is performed in common, i.e., both together, with respect to the gripper part of the folding cylinder, when the clutches are disengaged. During normal operation, the planetary-gear drives idle.
German Published Non-Prosecuted Application (DE-OS) 17 86 292 discloses a device for adjusting impaling pins on folding-blade collecting cylinders in folders of rotary printing machines. In this heretofore known device, impaling pins provided on a folding-blade collecting cylinder are controlled by follower rollers running on a control cam of a cam member. The cam is adjusted and, accordingly, the pins are operated by means of a helical ring gear and a helical gear, which are in meshing engagement with adjusting gearwheels mounted on an axially displaceable adjusting bolt. A disadvantage of this known device is the high outlay required for equipment to operate only one row of impaling pins on the folding-blade collecting cylinder.
European Published Non-Prosecuted Application (EP-OS) 0 385 818 discloses a device for cutting and folding a printed paper web. A folding cylinder carries at least one movable folding blade, which can be moved between two positions. It can either remain below the outer cylindrical surface of the folding cylinder or it can be used to form a second transverse fold, if such a fold should be desired. Through the intermediary of a V-shaped roller lever, it is possible to alternate between the retracted at-rest position and the extended working position.
The aforedescribed constructions of the prior art entail a considerable outlay for equipment to realize changeover operations of folding blades and impaling pins. The changeovers are performed manually to a very great extent, and are difficult to automate due to the complexity and the required fine adjustment.